Original page created on 16/05/2016.
Really functional lamps
REE era IV lamps
In 2015, REE proposed era IV lamps in bag of six parts. Like the (too) modern lamps currently fitted to the hopper, they are equipped with a light guide. So, I rightly thought that they were interchangeable and I immediately jumped at the opportunity to replace them.
Disappointment: the tail lamp body is shorter, and does not mask the bottom of the light guide. Therefore, almost all light passes under the lamp! And, due to the poor design of the guide (no 45° return at the end), the little light arriving at the end cannot practically be seen.
For some time now, I was meditating to replace this device with lamps equipped with an embedded LED. I had mounted an LED in ten REE lamps, and I had already equipped an LS Models TA60 wagon, without any difficulty, and then a Roco Est coach and a Jouef cereal hopper. I finally decided to equip the REE hopper.
Keep the original circuit or make a new one?
The question arose whether to retain the original circuit or not; very discreet, it allows running empty or loaded: it remains invisible. At the price of the suppression of the coupling, which prevents manoeuvring the wagon. But, as we saw before, I added an anti-blinking circuit to the wagon, hidden by a load. So, there was no longer question of running empty!
Another question: should we connect the new LEDs in place of the old ones? These are really tiny, and the risk is very great to destroy them when unsoldering. Better keep this circuit intact for possibly restoring the wagon in its original state.
All these considerations led me to eliminate purely and simply the original circuit and to make the choice of a new circuit, implanted into the hopper, combining all the required functions, namely:
- rectifier,
- energy supply,
- magnet control with bistable reed switch,
- power two LEDs in series.
Implementation
Current pickup
The solution adopted by REE, that of the strips rubbing on the inner side of the wheels, is not very satisfactory. In addition to the bad contacts already mentioned, there are other disadvantages, such as the braking of the wagon (accompanied by grinding) and the non-burnishing of the wheels to ensure correct electrical contact with the track. The solution of using conductive bearings in combination with non-insulated wheels half-axles is much better.
But these wagons do not have conductive bearings! Never mind. I installed them, according to the method already used for the Hornby Acho refrigerated wagon: digging the axle box with a spherical milling cutter in the drill mounted obliquely with respect to its descending axis.
The bearings, slightly bonded, are then connected by a strand of wire soldered on their shoulders, using flux, because the operation made directly on the spot must be fast. Finally, flexible wires are soldered in the same way and then connected to the control circuit. Attention: these wires must be very thin, under penalty of rubbing under the chassis of the wagon, thus hindering the bogie travel.
Conductive axles
I need four uninsulated wheels, which I am going to take from another wagon: for aesthetic reasons they must all have the same browned appearance, contrary to those of the original bogie; these will be mounted on the other bogie.
As usual, first disassembly of the insulated wheels on two axles and uninsulated wheels on two other axles. Reassembly of the insulated wheels on the axles which have retained their insulated wheels and immediately re-equipment of the donor wagon.
Cutting of the remaining axles (length of a half-axle: about 11 mm.) Repositioning of the wheels with an offset of 0.4 mm from their original position (the shoulder existing on the REE axle makes it possible to easily estimate the offset).
Assembly thanks to a suitable sleeve (ballpoint pen cartridge) of exactly 14 mm long, which automatically gives the wheel back-to-back distance of 14.5 mm (± 0.1). A suitable axle must have an overall length of 23.6 mm (originally 24.4 mm). This last dimension can be slightly modified if it is found that the rotation in the bogie is not free, or if there is too much clearance: this depends on the bearings used and their mounting depth. It is even possible to adjust this depth by carefully pressing the bearing with a thermoregulated soldering iron (about 150° C, not more!).
Stripping of wheels
The wheels used are burnished, and — according to REE — badly conductive. So, I stripped their rolling table until material appeared, which is brass (there is an intermediate copper layer probably to promote chemical treatment). And as the appearance obtained does not look really serious, I try to burnish again with brass burnisher, to check whether the conduction is correct. Well, yes it is!
Installing the lamps
Normally, the tail lamp supports are attached to the railing; but there is none! There is, nevertheless, a suitable support: the light guide itself. And as the REE lamps are designed to fit on, let’s enjoy it! So, they are glued on their guide (only slightly depressed, because of the presence of the LED).
The LED wires (⌀ 0.1 enamelled wires), cautiously twisted, since this is not the time to break them flush with the tail lamp, descend vertically on the buffer beam and then go towards the outside of the chassis, maintained by some superglue drops. Then they enter the hopper through the hole already drilled. They are painted in wagon red (approximate!)
Note that it is unfortunately impossible to mount an elongated drawbar, the proper part being missing. Or maybe a Makette KKK1?
Control and connection circuit
See the PDF document giving the diagram and the etching film of this circuit.
The circuit has two input terminals for the wires coming from the bogie and four terminals for those of the LEDs. The latter being in series, I could have connected two wires further upstream, but I find it more convenient to bring all the wires back to the same place. I have equipped the circuit with the 470 µF capacitor used before, which gives a lighting autonomy of more than ten seconds!
Circuit photographed before soldering the (present) reed switch and the capacitor (not present, its location being in the circuit centre). The bogie wires arrive to the left, and the lamp wires go to the right. The resistor R2 value (27 kΩ, marking 273) can be changed to set the LED brightness.
Result
It can be seen that the light passes through the walls of the lamps. Indeed, the material in which they are moulded is white! If it had been black… What a pity, isn’t it?
REE lamps ref. XB-502
€11.90 per 6 - price 2015
at jura-modelisme.fr